I got this randomly when playing. This happened when configuring flow direction of a pipe.

The mod Flow Configuration (3.0.1) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event flow-config::on_gui_opened (ID 104)
Fluid storage at the given index does not have a fluid segment.
stack traceback:
[C]: in function 'get_fluid_segment_fluid'
flow-config/flowlib/stateutil.lua:58: in function 'are_fluids_compatible'
flow-config/flowlib/stateutil.lua:186: in function 'is_blocked'
flow-config/flowlib/stateutil.lua:231: in function 'get_direction_states'
flow-config/control.lua:107: in function 'update_pipe'
flow-config/control.lua:270: in function <flow-config/control.lua:266>

stack traceback:
[C]: in function 'newindex'
__flow-config/control.lua:192: in function 'on_button_direction'
flow-config/control.lua:292: in function <flow-config/control.lua:286>

Hi artisauce! What are the other mods you have installed related to pipes? (what shows up in the modify list for pipes) I haven't been able to reproduce it, but I've tentatively fixed it with 3.1.2

Sorry for late, but I did manage to find the screenshot my friend took when it generally happened. I think it has something to do with Factorissimo 3. https://i.imgur.com/rTGKY0F.png